F'n fuel leaks!
 

i just completed an engine replacement in an S4 NA, and i started it up yesterday, with no problems except an oil leak around the main eshaft bolt, but i fixed that. today, i start it up to set the timing and everything, and fuel starts spraying from between the secondary injector and fuel rail. so i take it off to discover that the o-ring is partially cut. i replaced it with one from an S5 injector, then it was a slower fuel leak, just sort of dribbling down. i put another o-ring at the base of the injector upper grommet(so it would seal with the fuel rail) and it stoped leaking. THEN the primaries started leaking, BAD. WTF?! ive put injectors in and taken them out before many times on my S5, with no problems whatsoever. anybody have any ideas on better sealing methods than the o-ring?

POS S4s....

You have to use new seals and grommets. Old ones that are no longer soft will not work right. Also, check that the return line is properly attached and the pressure regulator and pulsation dampener is functioning properly. If excess fuel can't returning to the tank, or if there is a blockage, then fuel pressure will build and it will find a way to escape.

I had discovered the same problem with my one primary injector, Strtaed the car up was running for about 2-3 minutes, having hard time keeping a good idle and I decided to look around and check the BAC. Then I heard fluid running down the drian in my garage, looked under the car, and MY GOD!!!!! fule was POURING off of the block! I prolly lost a good 1/2gallon! I was lucky it didn't ignite! Anyways somehow the oring got cut. I replaced it wil a S5, and I do not smell or see and gasoline. For now I am carry a fire extinguisher with me!

You can usually reuse the upper orings provided they arent already flattened or cut. You HAVE to be sure the fuel rail is dry and the oring is lubed with oil or something .Slowly work it in in a circular motion into the rail and youll have no problems most of the time.

If the seals aren't the problem, you may want to check into the FPR. If it's bad, it will build up too much pressure in the fuel rails. Also, I noticed you have a Walbro. You probably need to get an updraged FPR to handle the pressure that the Walbro puts on it. Or it might just be worn out. Just a thought, hopefully it's the o-rings, they're cheaper. :D

its not my car im working on, its an S4 base. i thought i read something on here a while ago about someone using a peice of rubber hose or something in place of the o-ring, but i couldnt find it in a search